Field of the Invention
The present invention relates to a soldering system of a semiconductor laser element suitable to the manufacture of semiconductor laser modules, for example.
Related Art
Laser oscillators applied to laser processing machines used in cutting, welding, etc. of metal, resin materials, etc., are equipped with a semiconductor laser module as a light source or light source for excitation. The semiconductor laser module couples (optical coupling) the laser beam excited by the semiconductor laser element to optical fiber, and provides a laser to the laser oscillator through the optical fiber. The semiconductor laser module is configured to have a housing and one or a plurality of semiconductor laser elements. In such a semiconductor laser module, soldering is used in order to directly or indirectly (via another member) fix the semiconductor laser element(s) to the housing. It should be noted that, unless necessary to distinguish in particular, both the case of directly and the case of indirectly will be included in fixing of the semiconductor laser element to the housing.
The laser beam irradiated from the semiconductor laser element of the semiconductor laser module must be coupled to the optical fiber. In this case, the positional precision of the semiconductor laser element influences the coupling efficiency to the optical fiber. High positional precision, and parallelism between the semiconductor laser element(s) and housing (hereinafter referred to simply as “parallelism” as appropriate) are demanded in soldering of semiconductor laser elements. In the case of fixing semiconductor laser elements by soldering, a solder layer invariably exists between the semiconductor laser module and the semiconductor laser element. When performing soldering, the solder temporarily enters a molten state, the solder solidifies by cooling, and the semiconductor laser element is fixed to the housing. For the semiconductor laser element, soldering is performed in a state fixed by a robot hand; however, in the course of the solder layer temporarily melting and then cooling to solidify, it is possible for the positional precision and parallelism to deteriorate.
Although the light of the semiconductor laser element is coupled to the optical fiber by adjustment of the optical system of the semiconductor laser module, in the case of the positional precision of the semiconductor laser element deteriorating, the coupling state cannot be adjusted by adjustment of the optical system, and the coupling efficiency to the optical fiber deteriorates. Generally, the coupling efficiency to optical fiber cannot be determined until completing the semiconductor laser module, and measuring the output of the laser beam irradiated from the optical fiber. In addition, a semiconductor laser module having poor coupling efficiency as a result of the determination will be scrapped. Although it is possible to improve the coupling efficiency by re-adjustment of the position of the semiconductor laser element and optical system, the matter of dismantling a semiconductor laser module once completed and re-adjusting is not practical when considering the workload and cost of components that cannot be reused.
A method of determining general soldering quality by image recognition, and automatically correcting upon having a defect has been proposed thus far (for example, refer to Patent Document 1). In such a case, a method of determining positional precision using geometrical characteristic points from camera images has also been proposed thus far (for example, refer to Patent Document 2). In addition, technology which includes a plurality of cameras in a die bonder, and tries to achieve higher precision in image recognition by stereo vision has also been proposed (for example, refer to Patent Document 3). Furthermore, there has also been a proposal which configures a soldering device to include a robot and camera, and tries to improve the efficiency of soldering quality determination (for example, refer to Patent Document 4).
Patent Document 1: Japanese Unexamined Patent Application, Publication No. H05-063353
Patent Document 2: Japanese Unexamined Patent Application, Publication No. 2014-102206
Patent Document 3: Japanese Unexamined Patent Application, Publication No. 2006-324599
Patent Document 4: Japanese Unexamined Patent Application, Publication No. 2013-074231